Method of eliminating moisture problems in housing

ABSTRACT

Method of eliminating moisture problems in housing and premises with supporting structures made of concrete, comprising hydrophobic impregnation of a supporting concrete construction/bedding with a hydrophobic agent with a molecular size such that the impregnation becomes open to diffusion, and thereafter application of acidic ion exchange particles dispersed in a carrier on the bedding for the formation of a layer.

The present invention relates to a method of eliminating moistureproblems in housing and premises having a concrete supporting structure.

BACKGROUND

Most of the housing and premises in Sweden were built after 1945. Up tothe industrialization of the erection during the seventies,comparatively few different building materials were used. The experienceof these materials, such as stone, wood, bricks, concrete, sheet metaletc., based on few raw materials, was extensive. Concrete is a buildingmaterial which has been used in constructions built in situ as well asin prefabricated constructions. Concrete as a building material isformed when cement, gravel, stone and water is mixed in order to obtainthe desired properties. Nowadays concrete contains a large number ofchemical substances among other things in order to obtain bettercharacteristics in manufacture, transport and erection. Constructionconcrete for the supporting elements of the buildings such as the floorand the walls contains, among other things, Portland cement, thecharacteristics of which counteract damage of the reinforcement steel.

Flow putty is used to even out concrete floors before laying down thefloor covering, such as linoleum, PVC carpets and different types ofwooden floors. Flow putty is manufactured from cement, dried sand anddifferent additives. The most common flow additive formerly was casein,which is a protein which was added to flow putty in order to enhance theflowing-out properties. Now other additives are used, e.g. melamine.

The cause of the problems which are summarized under the term "sickhouses" can primarily be derived from the high moisture load, which e.g.the concrecte floors are subjected to during the building phase, as wellas the acute moisture damages in the form of "water damages" which occurduring the user phase of housing and premises. Nowadays it is known thathigh pH-values, e.g. an alcaline environment, creates a combinationeffect where for example PVC carpets and softeners therein as well ascarpet adhesives, are broken down by alcaline moisture from the concreteas well as when ammonia escapes from flow putty.

It is not only the moisture in itself that is the problem but also thecharacter of the moisture, i.e. its high pH-value, which is the reasonfor a large part of the sick-house-problems.

THE INVENTION

The object of the invention is to provide a method of substantiallyreducing the damages in view of health problems caused by the abovementioned technical deficiencies.

This is achieved with the method according to the present inventionwhich is characterized by hydrophobic impregnation of the supportingconcrete construction/bedding with the aid of a hydrophobic agent with amolecular size such that the impregnation becomes open to diffusion, andthereafter treatment of the bedding with an acid ionexchanger havingbeen mixed into a carrier.

Thanks to the hydrophobic impregnation future water uptake by theconcrete is reduced to a minimum while at the same time it is left todiffusion so that moisture is not confined therein. This is of utmostimportance for a tile on the ground in which the relative humidity canbe up to 100%. Preferably, silanes and/or siloxanes are used, which havea suitable molecular size. The acidic ion exchanger then takes care ofthe alcalinity of the moisture coming from the alcaline Portland cementand possible ammonia being formed at the degradation of flow putty etc.This means that the esther hydrolysis reaction which breaks downsoftening agents in e.g. PVC carpets and adhesives for floor carpets,normally a phtalic acid esther such as di(2-ethyl hexyl)-phtalate,practically ceases. The pH of the moisture should be less than 9, andpreferably be less than or equal to 8.

Hereby is achieved that, besides that the problems with sick houses arereduced or eliminated, the life of the floor carpets increases from oneor a few years to at least 15 years. The normal time of use for PVCcarpets in premises and housing are 8-10 years.

The choice of the ion exchange material is not critical but for the factthat it should be acidic for taking care of the OH⁻ ions in themoisture. By using an ion exchanger with H⁺ ions water is formed, whichis preferred. Examples of useful ion exchange materials are zeolites,sulfonated carbon and synthetic ion exchange resins.

The particles of the ion exchange material should have a size within theinterval 50-350 μm. The size of the particles within the interval isdecided depending on the surface layer chosen. Examples of suitableparticle sizes for different surface layers will be evident from thetable below.

Advantageously, 10-15% ion exchange particles are added, depending onthe particle size chosen and on the demands that are put on the newsurface layer, see the table below, to a carrier consisting of e.g. acopolymer of acrylic acid esther and styrene, in order for the ionexchange process to proceed at least during 15 years of time, whichexceeds the expected life of a PVC carpet which is 8-10 years. Further,a successive drying-out of the concrete occurs, wherefor the consumptiondiminishes. The amount and size of the particles is not decisive for thefunction of the invention, but these quantities are important forflowability and spreadability as well as the eveness of the beddingafter covering. In comparison it could be mentioned that if the moistureproblems should be eliminated without using the invention the concretewould have to be dried down to about 70% before application of a surfacelayer. The time required for this can be up to about 1 year for a normalconcrete floor.

The method according to the invention thus comprises two steps and theseare described below. 1. Hydrophobic Impregnation of the Bedding

The object of the treatment is to protect concrete and flow putty,respectively, against future water absorption. The agent used shall thuspenetrate into the mineral building material with low porosity, wherebythe small molecules of the agent form a water repellant layer on thecapillary walls, without the pores and capillaries, respectively,becoming obstructed. Thus, the construction shall be open to diffusionafter performed treatment. When treating of very dry underlying floorsof concrete and flow putty, the uptake of water diminishes from 25 ml/24hours to about 0.35-1.0 ml/24 hours at e.g. inundation or water leakage,i.e. a 25 times enhancement compared to constructions not having beentreated.

Hydrophobic impregnation pet se have been performed earlier on concreteconstructions, but then silicon-based products dissolved in white spirithave been used. Hereby the concentration of active component is onlyabout 25%. Already from environmental reasons this technique can not beused today. Further, the particles are large, in the order of magnitudeμm and instead of penetration a tacky covering is obtained.

Epoxy based products, which according to known technique are applied inlayers with 2-3 mm thickness, result in, among other things, that theunderlying floor becomes diffusion tight. When having a tile on theground, the concrete will have a constant high moisture content with ahigh pH-value and this moisture can act negatively on the epoxy layer,and does not give any long term solution to the problem of sick houses.

At hydrophobic impregnation of concrete according to the invention theimpregnation agent consists of a 100% active component, such asDynasalan® BHN, which is based on isobutyl triethoxy silane.

The molecules of this product have a dimension of about 1.85 nm (18.5Ångstroms), resulting in that it has a very high penetration capacity incomposite material such as concrete and flow putty, respectively.

At impregnation of porous materials, such as light weight concrete, sandstone, advantageously a solution diluted with water is used, such asDynasalan® BSM 2000, which is provided with a concentration of 20%active substance in water, and thus is also completely free of organicsolvants.

The control of the quality of the impregnation can be performed with newmethods. The impregnation agent can be mixed with a fluorescentsubstance, which in an alkylsilane based impregnation solution can befluorescin 2(3,6-di-hydroxyxantyl)-bensoic acid! or other substance withfluorescing characteristics and suitable solubility. After performedimpregnation the depth of the impregnation is thereafter controlled withthe aid of ultraviolet light. Previously known control methods such ase.g. the funnel method are limited in their use at e.g. laying of floorcarpets in housing and premises. This control method can also be used onhorizontal concrete constructions, such as the underside of bridges andtheir edge beams, which advantageously are impregnated in order tocounteract water and salt uptake. 2. Treatment With Ion Exchangers

As mentioned above it is not the moisture in itself that causes thedamages but instead the character of the moisture. Most of thesupporting elements of buildings such as the floors consist of concretewherein the cement paste is Portland cement. This type of cement hascharacteristics such as a high pH-value in order to limit corrosiondamages of the reinforcement steel. In construction concrete with anormal moisture content the pH-value normally lies between 11.0 and 13.This environment, possibly in combination with the previously uses flowputty products create a flow of alcaline moisture towards carpetadhesive and PVC carpets, whereby different substances are released,such as 2-ethyl hexanol when the softening agent isdi(2-ethylhexyl)-phtalate.

The other step of the method according to the invention comprises asurface treatment with ion exchanger having been mixed into, forexample, acrylic dispersions such as carpet adhesive and/or primer. Theparticle size of the ion exchanger in this connection preferably liesbetween 50 and 150 μm and get a very effective binding against theunderlying floor.

In summary, with the present invention is accomplished that

the bedding is protected from water uptake at e.g. water damages sincethe treatment results in that only a week increace of the moisturecontent in e.g. concrete floors is obtained during long and lasting"inundations",

the problems with the chemical degradation of the softening agents inPVC carpets are reduced or eliminated,

a low moisture content and a low pH-value in the concrete bedding isguaranteed,

a floor construction open to diffusion is guaranteed,

a lasting concept for healthy and water-proof floors and a good indoorclimate is created.

In the following table the presently preferred amounts of ion exchangermaterials in % pro litre acrylic dispersion dependant on the bedding inquestion is given; the presently preferred particle size depending onthe surface layer chosen; and finally a suitable amount of hydrophobicagent depending on the moisture content of the bedding.

    ______________________________________                                                     Dry ion exchange mass in %/                                                   liter acryl dispersion                                           Consumption of material/m.sup.2                                               for different types of subfloor                                                              50 μm 100 μm                                                                             200 μm                                                                            350 μm                              ______________________________________                                        Type of floor structure                                                       Concrete floor, on the ground                                                                20       25      30     35                                     Concrete floor, creep                                                                        20       25      30     35                                     foundation                                                                    Concrete floor, intermediate                                                                 10       10      20     25                                     Floor with top floor of tree, e.g. parquetry Floor with surface layer of      linoleum or PVC carpets                                                                       ##STR1##                                                      Hydrophobution                                                                Alkylsilane type CIAB* on                                                     very dry subfloor                                                             (w = 3%) = about 1.0-1.2                                                      liter/m.sup.2                                                                 Alkylsilane type CIAB* on                                                     moist subfloor                                                                (w = 5%) = about 0.6-0.7                                                      liter/m.sup.2                                                                 ______________________________________                                         *Alkylsilane type CIAB = Dynasylan BHN + Fluorescing substance           

We claim:
 1. Method of eliminating moisture problems in housing andpremises having supporting structures made of concrete, whichcomprises:hydrophobically impregnating a supporting concrete beddingwith a hydrophobic agent having a molecular size such that theimpregnation becomes open to diffusion, and thereafter applying on thebedding an acidic ion exchange material having particles dispersed in acarrier in order to form a layer on the bedding.
 2. Method according toclaim 1, wherein the hydrophobic impregnation is performed with at leastone of silanes and siloxanes.
 3. Method according to claim 1, whereinthe hydrophobic impregnation is performed with isobutyl triethoxysilane.
 4. Method according to claim 1, wherein the particles of the ionexchange material have a particle size within the interval of 50-350 μm.5. Method according to claim 4, wherein the ion exchange particles aredispersed in an adhesive intended for gluing a surface layer.
 6. Methodaccording to claim 5, wherein the adhesive is a PVC carpet adhesive. 7.Method according to claim 4, wherein the ion exchange particles aredispersed in a primer and are applied on the bedding before applying asurface layer.
 8. Method according to claim 4, wherein the ion exchangeparticles are dispersed in an acrylic dispersion.
 9. Method according toclaim 1, wherein the ion exchange material used is selected from thegroup consisting of zeolites, sulfonated carbon and synthetic ionexchange resins.